What is ash dieback?
Sadly, ash trees in the United Kingdom face a bleak future. Ash dieback (also known as Chalara fraxinea) is a highly infectious disease expected to result in the mortality of up to 95% of our ash trees.
This disease is caused by a fungus called Hymenosyphus fraxineus which originated in eastern Asia. It is primarily known to be spread by the wind blowing spores of the fungus far and wide. European ash trees were first recorded to be dying en masse in Poland back in 1992. Ash dieback was first confirmed in the UK in 2012 in Buckinghamshire though there is some evidence to suggest that it in fact arrived as early as 2006.
Not only is ash dieback a threat to our ash population, there are also unfortunately serious implications for biodiversity and ecology more widely. Ash trees support natural habitats for a huge selection of species. For example, insects, mosses, mushrooms and lichens rely heavily on ash to thrive.
There is some good news! Thankfully, research suggests that a small proportion of ash trees will not be affected by the disease. With their genetic tolerance to the fungus, this group of ash will survive, thrive and reproduce in the face of adversity helping to safeguard the next generation of ash trees.
Sadly, there is no proven cure to remedy this highly infectious disease. However, there are things that we can do to spot symptoms, help prevent the spread and take action to safeguard the health of each ash and prevent any harm to life or property.
How to spot it
- Blackened, wilting leaves
If an ash tree is infected, leaves will begin to blacken and wilt. You might notice discoloured or dappled leaves amongst green leaves. Infection will begin at the tip of the branch and work its way towards the trunk of the tree. This is most easily visible between July – September.

2. Bare branches
Most infected leaves will be shed prematurely resulting in the tree’s canopy appearing bare in comparison to other trees. Branches tend to dieback from the tip resulting in bare outer branches.

3. Dark lesions in bark
In some cases, infection can spread from the leaves into the twigs, then branches and eventually the trunk of the ash tree. These dark lesions are usually long thin diamond shapes which form at branch joints. Lesions at the base of the tree trunk weaken the trunk and increase the likelihood of the tree falling and causing harm.

How you can help
If you are out and about and think you have spotted an ash tree suffering from symptoms of ash dieback, you can report it using websites like TreeAlert or Observatree.
When venturing into woodland or areas densely populated by trees, you can help to reduce the risk of contaminating other areas by brushing any excess debris from your footwear or bike/pram wheels when leaving the area.
How we can help
Once an ash tree is infected, it can become structurally unsafe. As branches and stems dieback, the risk of falling deadwood dramatically increases. Not only can branches and limbs become fractured and fall, when a large, infected ash tree fails the potential damage can be devastating.
If you are concerned about the health of an ash tree on your property, our qualified arborists at Bencombe Tree Care can provide a detailed inspection. We can help to identify next steps to help safeguard the tree and reduce potential risk to life and property.
Simply give us a call, get in touch on social media or drop us an email and we would be happy to offer our advice.